no. 1640. NEW SPECIES OF FOSSIL TURTLES— HAY. 1(33 



HOPLOCHELYS CiELATA, new species. 

 Plate XXVII, figs. 1-3. 



The present species is based on rather meager remains, but it is 

 believed that they indicate clearly the position of the animal and will 

 enable one to identify other individuals furnishing the same parts. 

 The materials consist of a peripheral, thought to be the seventh of the 

 left side and the two succeeding ones; the eighth, ninth, and tenth of 

 the right side ; and some small fragments of costal bones. These have 

 the Cat. No. 5958 in the U. S. National Museum. These remains 

 were found by Mr. A. C. Silberling, in 1908, on section 35, township 

 6 north, range 15 east, being north of Big Timber, Sweet Grass 

 County, Montana. The beds are regarded as belonging to the Fort 

 Union epoch. The writer is informed by Mr. J. W. Gidley that the 

 mammalian remains indicate equivalence with the Torrejon of New 

 Mexico. 



A comparison of these bones with corresponding parts of Kinoster- 

 non integrum makes it probable that the carapace of the new species 

 had a length of about 114 mm. Fig. 1, Plate XXVII, gives a view of 

 the outer surface of the peripherals of the right side; while fig. 2 

 shows the inner surface of those of the left side. It is seen at once 

 from fig. 2 that the plastron articulated with the carapace principally 

 by means of finger-like processes sent into the bridge peripherals. It 

 seems quite certain that the upper borders of the peripherals were 

 joined to the costals by jagged sutures. Likewise, the ends of the 

 costal ribs entered deeply into the peripherals, as shown by the lower 

 vertebra of fig. 2. 



The peripherals are almost plane on their outer surfaces; on their 

 inner they are convex from the free border to two-thirds their height, 

 the upper third being concave. The free edge is acute. Probably a 

 sharp carina crossed fore and aft the peripherals of the bridge. The 

 peripherals present have the following lengths along the free border : 

 The seventh, 13 mm.; the eighth, 14 mm.; the ninth, 16 mm.; the 

 tenth, 16 mm. The seventh is 8.5 mm. thick at the front end; the 

 greatest thickness of the ninth and tenth is a little less than 5 mm. 

 On the inner surface of the peripherals behind the seventh the horny 

 scutes rose about half the height of the bones. 



The sulci that separated the various scutes are 'deeply and sharply 

 impressed. Those descending between the marginals are nearer the 

 front of their respective peripherals. What is regarded as the ninth 

 marginal is strongly angulated above, as is also the eleventh. 



A fragment of costal bone (Plate XXVII, fig. 3) has a maximum 

 width of 10 mm. and a thickness of hardly 2 mm. It is probably a 

 part of the seventh. 



The sculpture of this turtle will distinguish it from any related 

 Lower Eocene species yet known. The fragment of costal is crossed 



